Advances in Cement Research, 2013, 25(1), 1–14 http://dx.doi.org/10.1680/adcr.12.00059 Paper 1200059 Received 10/10/2012; revised 08/11/2013; accepted 11/11/2013 Published online ahead of print xx/yy/zzzz ICE Publishing: All rights reserved Advances in Cement Research Volume 25 Issue 1 Influence of aluminium inclusions on dielectric properties of three-phase PZT–cement–aluminium composites Banerjee and Cook-Chennault Influence of aluminium inclusions on dielectric properties of three- phase PZT–cement–aluminium composites Sankha Banerjee Mechanical and Aerospace Engineering Department, Rutgers, The State University of New Jersey, Piscataway, NJ, USA Kimberly A. Cook-Chennault Mechanical and Aerospace Engineering Department, Rutgers, The State University of New Jersey, Piscataway, NJ, USA Novel three-phase piezoelectric composites that comprised lead zirconate titanate (PZT), aluminium and Portland cement were fabricated at a low poling voltage of 0 . 6 kV/mm and temperature of 1608C. Aluminium and PZT particles were distributed in a Portland cement matrix, and the dielectric constant, tan ä and strain coefficients were experimentally investigated as a function of inclusion volume fraction. The three-phase piezoelectric composites were found to possess higher piezoelectric strain coefficients, d 33 , than their two-phase counterparts (PZT and Portland cement composites). The highest value of d 33 observed for the three-phase composite was 8 . 1 pC/N for volume fractions of 0 . 7 and 0 . 2 for PZT and aluminium respectively, which was 164% of the value observed for the two-phase composite, at the same PZT volume fraction. An analytical model was used to predict values for the effective dielectric constant of the three-phase composites, and these values compared reasonably well to the empirical data. An investigation of sample degradation as a function of time was performed. Samples showed the highest degree of reduced dielectric performance occurred within two days of data capture, and minimal subsequent reduction in performance after 300 days. Electrical properties of the composites are influenced by the oxidation of aluminium by the alkaline constituents in the cement matrix, distribution of PZT and aluminium within the matrix, particle agglomeration, inclusion size, contact resistance between particles, and air voids. The increased dielectric and piezoelectric strain coefficients, demonstrate that these types of materials may be useful in applications such as structural health monitoring and energy harvesting. Notation â calculated value, â ¼ (å PZT  å Cement )/(å PZT +2å cement ) å effective dielectric constant å cement dielectric constant of cement å PZT dielectric constant of PZT å 0–3 effective dielectric constant of the PZT–cement composite å 0–3–0 effective dielectric constant of the PZT–aluminium– cement composite ö Al volume fraction of aluminium ö PZT volume fraction of PZT Introduction Two-phase cement based piezoelectric composites have attracted much attention over the past decade due to their potential application in structural health monitoring (Blanas and Das- Gupta, 2000; Olmi et al., 2011; Ou and Li, 2010) as sensors in civil structures (Chaipanich, 2007a; Chaipanich and Jaitanong, 2008; Chaipanich et al., 2010; Chen et al., 1998; Cook- Chennault et al., 2008a, 2008b; Dong and Li, 2005; Gong et al., 2009; Huang et al., 2004b), such as high-rise buildings, bridges, nuclear waste containment structures, and so on, which are often subjected to severe dynamic loading that can lead to internal damage. Use of piezoelectric cement-based sensor and actuators for structural health monitoring and active vibration control of civil structures has been studied by (Brunner et al., 2009; Chen et al., 1998; Guratzsch and Mahadevan, 2010; Olmi et al., 2011; Sabra and Huston, 2011), and are considered favourable candidates for this application because homogeneous piezoelectric ceramics exhibit high dielectric constants and piezoelectric strain coefficients (Bhattacharya and Tummala, 2000; Kim et al., 2004; Ulrich, 2004). The inherent brittleness of homogeneous piezoelectric ceramics, high acoustic impedance and relatively high density, make them unsuitable for application to cement-based structures because of material incompatibility with the host structure, which is typically cement (Dong and Li, 2005; Li et al., 2002, 2005). Material properties for ceramic lead zirconate titanate (PZT) and Portland cement are detailed in Table 1. Composite materials can be used to address the issue of material incompatibility; however, the most rigorously studied Article Number = 1200059 1